As is well known in the prior art, a seat belt assembly for a vehicle is a device for protecting a passenger during an accident, such as a collision. The seat belt assembly mainly comprises a belt, a guide anchor for guiding the belt, a pillar for supporting the belt and the guide anchor to a vehicle frame, a retractor for holding the passenger in such a manner of fixing the belt instantaneously upon the collision while allowing the belt to move according to a movement of the passenger by restoring force in a normal state, and a free tensioner.
Among these components, the guide anchor is a component equipped to allow the pillar of the vehicle frame to freely shake in forward and backward directions while guiding the belt as it passes through the guide anchor. The guide anchor has numerous constructions according to manufacturers.
FIG. 1 shows a typical construction of a conventional guide anchor. The guide anchor of FIG. 1 is disclosed in Japanese Patent Laid-open Publication No. 2001-63517.
As shown in FIG. 1, the guide anchor comprises a metallic guide plate 11 for supporting a weight, a guide piece 12 through which the belt slides, and a resinous body 6 molded over the guide plate 11 and the guide piece 12 in a fixed state.
Here, since the guide plate 11 is temporarily coupled to the guide piece 12 by resilient press-fitting before injection of resin, there is a high possibility of misalignment between components during molding due to a significantly unstable coupling force.
FIG. 2 shows a construction of another conventional guide anchor. The guide anchor of FIG. 2 is disclosed in Japanese Patent Laid-open Publication No. 2002-104133.
As shown in FIG. 2, the guide anchor comprises a metallic guide plate 2 for supporting a weight, a guide piece 3 through which the belt slides, and a molding part 6 molded over the guide plate 2 and the guide piece 3 in a fixed state.
Molding is performed in a state that the guide piece 3 is temporarily fixed to the guide plate 2 before molding. As a result, it is possible to prevent the guide piece 3 from being separated from the guide plate 2 during molding or conveying. The construction of this guide anchor will be described in detail as follows.
The guide piece 3 is formed at a lower portion with flanges, each having a bent portion. A belt guide 5 of the guide plate 2 is formed with latching protrusions. Thus, when fitting the guide piece 3 into the guide plate 2, the guide piece 3 is resiliently deformed, and is then coupled to the guide plate 2 by wedge effect between the bent portions of the flanges and the latching protrusions, whereby the guide piece 3 can be firmly fixed to the guide plate 2 temporarily.
However, since the latching protrusions must be previously formed on the metallic guide plate 2, there is difficulty in manufacturing the guide anchor. Moreover, since the coupling force between the latching protrusions of the guide plate 2 and the bent portions of the guide piece 3 is insufficient during coupling, there is a possibility of slight misalignment therebetween.
FIG. 3a shows a construction of still another conventional guide anchor. The guide anchor of FIG. 3a is disclosed in Japanese Patent Laid-open Publication No. 2003-89345.
As shown in FIG. 3a, the guide anchor has plural protrusions 25 formed at an angle on a slip surface 24b in order to prevent the belt 23 from being biased upon collision. At this time, a slant angle θ1 of the protrusions 25 is related to an angle θb of a perforated direction of a guide hole 24a of the belt 23.
FIG. 3b shows a guide anchor disclosed in Japanese Utility Model Laid-open Publication No. (Hei) 5-44719. This guide anchor also has a slant groove 23 formed on a steel guide piece 22 such that a slant angle of the groove 23 is substantially identical to an angle of the belt S.
Although the above disclosures suggest the guide anchors of FIGS. 3a and 3b be constructed by suitably mounting the guide piece to the guide plate and then molding them or by integrally manufacturing the guide piece and the guide plate with metal or resin, detailed process and construction thereof are not illustrated in both disclosures.